One trend in the information technology (IT) industry is moving to end-to-end security solutions. The implication for an enterprise is that a server has to handle thousands of security associations at a time. For the forensics and auditing, tracking that many security associations is not an easy task in terms of IT computing resources. Due to the cost of cryptography hardware, it is expensive to store thousands of keys and their associate information in hardware buffers and perform cryptography operations for individual security associations. Even if such keys were to be stored in the main memory, the delay caused by fetching the corresponding key for a frame would significantly increase the latency for processing a packet in hardware. Thus, the frames of a 10 Gbps link may congest at the hardware buffer and undergo undesirable packet drop.
Additionally, point-to-point security associations require unique session keys that are typically established at the start of each session. Negotiating these session keys is time consuming using a Diffie-Hellman key exchange and adds substantial protocol overhead. For example, to exchange a single data packet might require negotiation involving the exchange of several additional packets to establish the new session.
In a corporate intranet, it is feasible to deploy group-based security schemes involving shared security association where a few clients share the same key with an application server. Then, the application server can use one key to process all the packets coming from those clients. As such, the number of security associations can be reduced and the keys can be installed in the hardware, which is attractive for an economic solution to high-speed hardware security associations.
However, while shared key solutions remove the need for high latency session negotiation overhead and key management complexity by allowing trusted devices to use the same session key for cryptographic operations, compromises are nearly impossible to trace back to the source causing potential security vulnerability.